1. Field of the Invention
The field of the invention is a numerical control system for machine control using a stored program data processor; particularly for coordinate resolution of motion commands.
2. Prior Art
The prior art uses mechanical fixtures to align parts, precomputed coordinates punched on tape, and non-computerized numerical control systems; wherein prior art numerical control systems do not provide computerized coordinate resolution capability.
Numerical control systems are used to control machines such as machine tools. Digital parts program commands are input with a punched tape to describe the part to be cut on a machine such as a milling machine. These parts program commands are accessed from the tape by the numerical control system and are executed to drive the machine to automatically cut the part.
Prior art numerical control systems have been designed around special purpose digital devices where operations such as logic, control, and computations are performed with special purpose logic. Because of the high cost and limited capability of these special purpose numerical control systems, most of the computations are preprocessed with a remote, large scale computer using a parts program compiler such as APT. The remote computer preprocesses the information and generates a punched tape in a control oriented language containing the initial conditions and commands required by the special purpose numerical control equipment. These parts program tapes describe the part to be generated and are used as the command inputs to the numerical control system to cut the part.
The limited capability of the prior art, non-computerized numerical control systems have placed a considerable burden on the parts programmer, system operator, and the entire manufacturing organization. In prior art systems; parts programming requires many unnecessary calculations, workpiece setup and equipment operation are complex, and manufacturing control is very limited. Other problems are encountered due to the limitations of the prior art numerical control systems.
A numerical control system usually includes a machine control unit (MCU) and a machine, wherein the MCU and the machine are located together. A DNC system usually includes a remote computer center, a data link, an MCU, and a machine; wherein the MCU and machine are located together and wherein the MCU communicates with the remote computer center over the data link. In many DNC systems the MCU and machine may be a conventional numerical control system, wherein the MCU has a data link interface in place of or in addition to the usual tape reader.